Many types of spinal irregularities can cause pain, limit range of motion, or injure the nervous system within the spinal column. These irregularities can result from, without limitation, trauma, tumor, disc degeneration, and disease. Often, these irregularities are treated by immobilizing at least a portion of the spine. This treatment may include a fusion between adjacent vertebrae. There are a number of known conventional fusion devices and methodologies in the art for accomplishing intervertebral fusion. These include screw and rod arrangements, bone implants, and fusion devices which include a cage or other implant mechanism which may be packed with bone and/or bone growth inducing substances, for example. With certain fusion devices, the intervertebral disc may be partially or fully removed. An intervertebral fusion device may then be inserted between neighboring vertebrae to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion and alleviating the associated pain.
The risk of injury to a nerve is a concern when performing surgical procedures in close proximity to the spine or spinal nerves. In particular, minimally invasive surgical procedures with small incisions limit direct visualization of the targeted site. For example, endoscopic procedures may be performed through a cannula or endoscope working channel with a limited amount of access to the surgical site. Surgeons increasingly rely on neuromonitoring techniques to monitor the nerves during such surgeries in order to avoid inadvertently injuring or contacting a nerve. Neuromonitoring functions to determine the integrity of a neural structure or the proximity of a surgical tool or instrument to that neural structure and to minimize contact or trauma to the area. There remains a need for enhanced neuromonitoring tools and techniques especially for use during minimally invasive or endoscopic spinal fusion procedures.